1. Field of the Invention
The present invention relates generally to captive fasteners.
2. Brief Description of the Prior Art
Captive screws are fasteners that are “captivated” or held within a collar or ferrule. The ferrule is mounted in a first panel or like object. The screw portion is captivated so that it can be moved perpendicular to the first panel and the screw's threads can engage a corresponding aperture in a second panel, so that the first and second panels can be secured together. However, when the panels are unscrewed and disengage, the screw is retained in the first panel. Captive screws are useful in applications where it is important to avoid dropping or losing screws during assembly or repair, such as electronic devices, where a lost screw can cause catastrophic electrical shorts damaging equipment.
Similarly, although in some applications, a workpiece can be drilled and tapped to receive and secure a screw, in other applications separate nuts are required to secure screws. In some of these applications it is also important to avoid dropping or losing nuts during assembly or repair, in order to avoid possible catastrophic electric shorts damaging equipment. For such applications, nuts can be provided with mounting means so that such nuts can be permanently fixed on a suitable surface. By analogy with the term “captive screws,” such nut can be referred to as “captive nuts,” and captive screws and captive nuts can be referred to as types of captive fasteners.
Captive screws necessarily stand out above the panel or door in which they are captivated. In certain applications, however, the extension of the captive screw above the panel can have an adverse functional or aesthetic effect. Similarly, in certain applications, the extension of surface-mounted nuts above the mounting surface or panel can also have an adverse functional or aesthetic effect.
In such cases, it would be desirable to reduce the extent to which the captive screw or surface-mounted nut extends above the panel, such as when a captive screw has been engaged by the lower panel or frame that the captive screw is intended to engage. However, at the same time, the captive fastener must be long enough to provide secure fastening between the panels or door and frame. It would be desirable to provide for secure fastening while simultaneously reducing the extent to which the captive fastener extends above the panel in which it is captivated, when the captive fastener is engaged.